Transfer mechanism with rotatable work engaging means



Nov. 16, 1965 J. L. BARKOCY 3,217,343

TRANSFER MECHANISM WITH ROTATABLE WORK ENGAGING MEANS Filed May 6, 1963 3 Sheets-Sheet 1 m m r- IIO F G.l

JJ HO INVENTOR.

JOHN L. BARKOCY W, M,

ATTORNEYS 3 Sheets-Sheet 2 INVENTOR.

JOHN L. BARKOCY MW, 0%

J. L. BARKOCY TRANSFER MECHANISM WITH ROTATABLE WORK ENGAGING MEANS Nov. 16, 1965 7 Filed May 6, 1963 (W ATTORNEYS Nov. 16, 1965 J. L. BARKOCY 3,217,343

TRANSFER MECHANISM WITH ROTATABLE WORK ENGAGING MEANS Filed May 6, 1965 3 Sheets-Sheet 3 INVENTOR.

JOHN L. BARKOCY BY W wan/491W ATTORNEYS United States Patent Ohio Filed May 6, 1963, Ser. No. 278,495 8 Claims. (Cl. -166) This invention relates to transfer mechanism for moving articles from one Work station to another, such as for moving blanks from one to another of a row of dies being used in cold-forming of the blanks.

An object of the invention is to provide novel transfer mechanism for this purpose which is relatively simple as compared with previous mechanisms and which is capable of operation at high speed with minimum noise and vibration and with a minimum tendency to cause throwing of the blanks.

Another object is to provide novel transfer mechanism in which holder units for the articles are located immediately adjacent the face of the die mount and will operate successfully even while in contact with such face, for either a direct transfer movement of the articles or for a turn-over transfer movement thereof when desired.

These desirable features and advantages are achieved to an important extent from the fact that the holder units of the mechanism are of a balanced character from the standpoint of symmetry and distribution of weight relative to the rotation axis of the turn-over movement, so that die slap is Wholly eliminated as well as any eccentric or gyratory movements tending to cause shock or centrifugal effects.

The very close or contacting position of the holder units relative to the face of the die mount is important because the articles are then located closer to the die openings for a more direct and accurate movement thereinto. With this relative location for the holder units, the associated punches need only be of a short length and are therefore less subject to breakage. Furthermore the ram of the header or the like, with which the transfer mechanism is being used, need have only a short operating stroke and can therefore be run at a faster production rate.

Still another object is to provide novel transfer mechanism in which carrier means thereof has a space or opening for receiving an article and also has substantially axially aligned holder members engageable with opposite sides of the article from axially opposite sides of the openmg.

A further object is to provide a novel transfer mechanism of the character just above mentioned in which one of the holder members comprises a positioning means against which the article is clamped by axial closing movement of the other holder member.

Yet another important object is to provide novel transfer mechanism of the kind referred to above in which one of the holder members is rotatable for imparting a turnover movement to the article while it is being held in the opening of the carrier means.

Additionally, this invention provides novel transfer mechanism of the above-mentioned character in which the holder members are embodied in a holder unit and preferably are disposed in axially aligned passages thereof, and the lower holder member is so supported that if breakage 3,217,343 Patented Nov. 16, 1965 occurs the lower portion of the holder unit will drop free .for lessening the likelihood of damage to the dies.

Other objects, novel characteristics and advantages of this invention will be apparent in the following detailed description and in the accompanying drawings forming a part of this specification and in which,

FIG. 1 is a front elevation of novel transfer mechanism embodying this invention and shows the mechanism with one of the holder units thereof in vertical section;

FIG. 2 is a top plan view of the transfer mechanism; and

FIG. 3 is a side elevation of the transfer mechanism and also shows the associated ram in its closed poistion but with the die punches omitted.

A preferred embodiment of the novel transfer mechanism 10 is shown in the accompanying drawings and comprises, in general, a support means 11 having a laterally extending guideway 12, a carrier 13 operable in the guideway, and a plurality of holder units 14, 15, 16 and 17 on the carrier and movable thereby to different article feeding positions adjacent a row of spaced work stations which are here represented by die members 18, 19, 20, 21 and 22. The holder units 14, 15, 16 and 17 are here shown as supporting articles 23, 24, 25 and 26 in feeding positions in front of the die members 19, 20, 21 and 22.

The transfer mechanism 10 can be used in conjunction with different kinds of apparatus and for handling various different articles, but transfer mechanism of this kind is commonly used with cold heading machines and, by way of example, the apparatus 10 is here shown in conjunction with such a cold heading machine 29. The machine 29 is here represented by the die mount portion 30 thereof and by a reciprocable ram 31 which is movable toward and away from the die mount. The dies 18, 19, 20, 21 and 22 are here shown in a laterally extending row (see FIG. 1) and are seated in recesses 32 which extend into the die mount 30 from the vertical front face 33 thereof.

The support means 11 is shown as comprising a laterally elongated body or head 35 resting on the top surface 36 of the die mount 30 and normally held against such surface by screws 37. The support means 11 is shown as also comprising a laterally elongated bracket 39 secured on the machine 29 by suitable screws 40 and having projecting eye-shaped lugs 41. The head 35 is pivotally connected with the bracket 39 by means of a hinge rod 42 received in the openings of the lugs 41. The pivotal connection of the head 35 with the bracket 39 permits an upward and rearward swinging of the head by which the holder units 14, 15, 16 and 17 can be moved away from the front of the die mount 30 to afford free access to the die members 18, 19, 20, 2-1 and 22.

The guideway 12 is formed by a pair of lower and upper V-shaped grooves 12 and 12 of which the lower groove is formed in the head 35 and the upper groove is fromed in a cover member 45. The cover member 45 is secured to the head 35 as by suitable screws 46 to which further reference will be made hereinafter.

The carrier 13 comprises a laterally elongated body 47 having V-shaped portions 48 and 48 slidably operable in the guideway grooves 12 and 12 The carrier body 47 is provided with a plurality of laterally spaced vertical openings 50, 51, 52 and 53 in which the holder units 14, 15, 16 and 17 are mounted. The carrier 13 includes cap members 54, 55, 56 and 57 by which the holder units 14, 15, 16 and 17 are secured in place and which cap members are connected with the carrier body 47 by clamping screws 58.

The center-to-center spacing of the openings 50, 51, 52 and 53 corresponds with the center-to-center lateral spacing of the die members 19, 20, 21 and 22 so that the holder units 14, 15, 16 and 17 extend in front of and across the die members when the holder units are moved to article-feeding positions by the carrier 13. The reciprocation of the carrier 13 will move the holder units from one to another of different such article-feeding positions adjacent the die members. In the transfer mechanism 10, as here illustrated, the holder units 14, 15, 16 and 17 are vertically disposed and the lower ends thereof extend across the die members in a depending relation from the carrier body 47.

The holder units 14, 15, 16 and 17 are all of the same construction. It will therefore be necessary to describe only one of these units and the carrier unit 17 is selected for this purpose. Before proceeding with the description of the carrier unit 17, it is pointed out, however, that the articles 23, 24, 25 and 26 are here shown as being nut blanks which are being progressively shaped to a desired hexagonal form by the dies 19, 20, 21 and 22 and by suitable punches (not shown) co-operable with the dies and normally carried by the ram 31.

The die member 18 is a cut-off die and represents a cutoff station at which the slug-like article 23 was severed from the lead end of a piece of wire stock 59 being fed through the cut-off die. The article 24 represents a partially formed nut body resulting from a first forming operation carried out in the die member 19. The article 25 represents the condition of the nut body after further forming thereof carried out in the die member 20. The article 26 represents the nut body after forming thereof in the die member 21 and is shown in a feeding position to be carried into the die member 22 by the associated punch of the ram 31 for a final piercing operation on the article for forming the top opening therein. The articles 23, 24 and 25 are likewise shown in FIG. 1 in feeding positions from which they are ready to be moved into the die members 19, 20 and 21 by the associated punches.

The holder unit 17 comprises an upper sleeve member 60 having a passage 61 and a lower block member 62 connected with the sleeve member and spaced from the lower end thereof so as to provide the unit with a transverse opening 63 for receiving the article 26. The block member 62 is here shown as connected with the sleeve member 60 by a pair of spaced arms 64 and 65 which span the opening 63 and are located on opposite sides of the central vertical axis 66 of the holder unit.

The arms 64 and 65 are here shown as being strip-like members which are secured to the sleeve member 17 by screws 67. The block member 62 is connected with the arms 64 and 65 only by pins 68 which project from the block and extend into openings of the arms. This form of connection between the arms 64, 65 and the block 62 has the advantage that, in the event of breakage of one of the arms, the block can drop free instead of remaining in a dangling position in which it might cause damage to the dies.

The holder unit 17 also comprises upper and lower article holders 71 and 72 disposed on the central axis 66 and which are located at vertically opposite sides of the opening 63 and engage the article 26 on opposite sides thereof. The upper holder 71 comprises a hollow spindle 70 disposed in the axial passage 61 of the sleeve member 60 and an upper gripping member 73 on the end of the spindle and projecting into the opening 63. The gripping member 73 is connected with the lower end of the spindle 70 by a rod 74 extending through the passage of the spindle.

The gripping member 73 has an article engaging portion on the free lower end thereof which is shaped to cooperate with the particular article to be handled by the holder unit 17. The article engaging portion of the gripping member 73 is here shown as being a recess of an axially converging shape, in this case, a V-shaped notch 75. The V-shaped notch 75 is suitable for all of the articles 23, 24, 25 and 26 and produces a self-centering action on the articles during the gripping engagement therewith.

The centering action of the notch 75 tends to center the article 26 on the axis 66 which is highly advantageous for a balanced condition of the holder unit 17 and for an accurate positioning of the article with respect to the opening of the die member 22 into which the article is to be moved. The notch 75 also produces a drive connection between the gripping member 73 and the article 26 by which rotation can be imparted to the latter when a turnover movement of the article is desired, as will be further explained hereinafter.

The lower holder 72 comprises a stem 77 and a lower gripping member 78 carried by the stem and here shown as being a head formed thereon. The lower holder 72 is located in an axial passage 79 of the block member 62. in which the gripping member 78 is slidably guided. A counterbore in the passage 79 provides a spring recess 80 in which a compression spring 81 is disposed and is effective between the bottom of the spring recess and the underside of the gripping member 78. The expansive action of the spring 8-1 tends to move the lower gripping member 78 toward the upper gripping member 73 for clamping the article 26 against the latter. The lower gripping member 78 therefore acts as a thrust member for applying thrust to the article 26.

The notch 75 of the gripping member 73 extends transversely thereacross, as can be seen from the illustration of the holder units 16 and 17 in FIG. 1, so that the articles can be readily moved into and out of gripping position between the members 73 and 78. For this same purpose the upper surface of the gripping members 78 is shown as having a flat area 82 located on and surrounding the axis 66 for contact with the article 26 in clamping the same against the gripping member 73. The gripping member 78 also has a chamfer 83 extending therearound outwardly of the flat area 82. The charnfer 83 and the flat area 82 permit the article 26 to be readily moved into and out of the gripping position between the members 73 and 78.

The upper holder 71 also serves as a positioning member for the article 26 for vertically locating the same in proper alignment with the opening of the associated die member 22 when the article is clamped against the upper gripping member 73 by the lower gripping member 78. The upper holder 71 is axally adjustable in the passage 61 of the sleeve member 60 for thus properly positioning the article 26 relative to the opening of the die member 22. For this adjusting purpose, the holder unit 17 is provided with a counterbore 85 in the sleeve member 60 and a hardened tubular spacer insert 86 of a predetermined length in the counterbore and engageable by an annular shoulder projection 87 of the spindle 70.

A compression spring 88 located in the counterbore 85 in a surrounding relation to the spindle 70 is effective against the annular shoulder 87 for holding the gripping member 73 in a position projecting into the opening 63 a proper distance for correctly positioning the article 26 when the latter is clamped against this gripping member by the thrust of the lower gripping member 78.

The upper end of the spring 88 is seated against a second hardened insert ring 90 received in the counterbore 85 in a surrounding relation to the spindle 70. A cover member 91 suitably secured on the upper end of the sleeve member 60 has a reduced portion extending into the latter to provide an abutment for the insert ring 90 and which abutment absorbs the thrust of the compression spring 88. The cover members 91 of the holder units are here shown as being connected with the sleeve members 60 thereof by set screws 92 extending through the wall of the sleeve members.

The position of the gripping member 78 of the lower holder 72 can be also be adjusted axially of the unit 17 and, for this purpose, the stem '77 has a threaded portion 93 projecting from the block member 62. Nuts 94 mounted on the threaded portion 93 provide a stop for limiting the upward movement of the lower gripping member 78 by the compression spring 81 and normally hold this gripping member at a spaced distance from the upper gripping member 73 to permit the article 26 to be readily moved into and out of gripping position between these members. A washer 95 is preferably used on the threaded stem portion 93 immediately above the nuts 94 and the adjustment of the lower holder 72 is normally such that when the article 26 is being held in its proper feeding position, a small clearance space will remain between the washer and the bottom of the block member 62.

The unit 17 is vertically adjustable in the carrier 13 upon loosening of the clamping screws 58 of the cap 57 for locating the upper gripping member 73 in the desired position relative to the opening of the die 22. The vertical adjustment of the lower gripping member 78, together with the adjustment just described for the unit 17, makes possible the proper positioning of the gripping members 73 and 78 to suit the size of the particular article being handled.

Althought the upper holder 71 has been described above as being a positioning or abutment means for properly locating the article 26 and the lower holder 72 has been described as a thrust means for clamping the article against the gripping member 73, these functions can be reversed and, if desired, the lower holder 72 can be the positioning or abutment means for the article and the upper holder 71 can be the thrust means.

The carrier 13 is reciprocably movable in the guideway 12 as by a link 96 suitably connected with the carrier body 47. Movement of the carrier 13 in a forward direction carries the holder units 14, 15, 16 and 17 to the positions shown in FIG. 1 and, in so doing, the holder unit 14 is moved from a first work station represented by the cut-off die 18 to a feed position in front of the die member 19. Similarly, the holder unit is moved from the die member 19 to a feed position in front of the die member 20, and the holder units 15 and 17 are moved from positions in front of the die members 20 and 21 to feed positions in front of the die members 21 and 22. During the return travel of the carrier 13 the holder units 14, 15, 16 and 17 are moved back to article-receiving positions in front of the die members 18, 19, 20 and 21, respectively.

For some of the die operations being performed on the articles it may be desirable to reverse the position of one or more of the articles as they are being transferred from one work station to another. Such a turnover movement is usually not needed for the article 23 which has not yet been subjected to any forming operation. On the other hand, it is usually desirable in the further forming of the articles 24, 25 and 26 to reverse the position of these articles. In the transfer mechanism 10 provision is made for such a turn-over movement for some or all of the articles being handled by the holder units 14, 15, 16 and 17.

For the purpose of such a turn-over movement of the articles, the upper holders 71 are rotatable in the sleeve members 60 of the holder units 14, 15, 16 and 17 and are provided with gear members 97, 98, 99 and 100 which are adapted to be driven for causing such rotation. The gear members 97, 98, 99 and 100 are located at the top of the holder units and are adapted for selective meshing engagement with a stationary rack 101 which is of a greater width than the gear members to permit the above-described vertical adjustment of the units 14, 15, 16 and 17. The rack 101 is shown as mounted on the cover member of the support means 11 and is secured in place by the screws 46. The rack 101 is adjustable toward and away from the gear members 97,

6 98, 99 and to a limited extent by the provision of set screws 99 in the cover member 45 and by clearance openings 102 in the rack through which the screws 46 extend.

The gear members 97, 98 99 and 100 are in the form of gear segments and are all of the same size and shape and have a toothed peripheral portion of an angular extent somewhat more than 180". Each gear member is truncated at one side thereof, as indicated at 103, so as to be devoid of teeth on that side, and the truncated side is provided with a recess 104. Each gear member also includes a clamping cap received in the recess 104 and by which the gear member is secured on the upper end of the spindle 70 of the associated holder 71. The cap 105 is secured in such a clamping relation as by screws 106.

From the description given above it will be seen that the upper holder 71 consists of the spindle 70, the gripping member 73, the rod 74 and the gear member 100. The spindle 70 and the rod 74 are of a length to extend somewhat above the gear member 100. The rod 74 carries a head 108 whose clamping action is applied to the upper end of the spindle 70 through a cap 109 seated on the latter. I

Since the gear 100 is secured on the spindle 70 of the upper holder 71 this holder will be rotatably driven by the gear 100 when the latter is in mesh with the rack and longitudinal movement is imparted to the carrier 13. This rotation of the holder 71 will rotate the gripping member 73 thereof to thereby drive the article 26 for reversing the position of the latter. During the reversing movement of the article 26 the side thereof engaged by the lower holder 72 pivots freely on the gripping member 78 by rotative sliding on the flat area 82 of the latter.

For all of the articles to which a turn-out movement is to be imparted, the gear members of the corresponding holder units are disposed in meshing engagement with the rack 98. The gear members 98, 99 and 100 of the holder units 15, 16 and 17 are shown in the drawings in such meshed engagement with the rack 98. Since a turn-over movement is not needed for the article 23, the gear member 97 of the holder unit 14 is disposed in a relative position so that the truncated side 103 thereof is presented toward the rack 98 and this position of the gear member renders the rotating means for the upper holder 71 of this unit ineffective.

It will therefore be seen that, during the reciprocation of the carrier 13, the upper holders 71 of the holder units 15, 16 and 17 will be rotated by the gear members 98, 99 and 100 to cause the desired turn-over movement of the articles 24, 25 and 26, whereas no rotation of the upper holder of the unit 14 will be produced by the gear member 97 and the article 23 will therefore be moved from the first work station represented by the cut-off die 18 to the second work station represented by the forming die 19, without any such turn-over movement.

Each of the gear members 97, 98, 99 and 100 have a lug projection thereon and which can be selectively located by a selected positioning of these gear members. In the case of the holder units 15, 16 and 17 which provide a turn-over movement for the articles 24, 25 and 26, the lugs 110 project upwardly and occupy a parked or idle position which does not prevent rotation of the gear members. In the case of the unit 14 however, which does not operate with a turn-over movement for the article 23, the gear member 97 has been inverted so that the lug 110 thereof is in a downwardly extending position.

When the lug 110 of the gear member 97 extends downwardly as just mentioned, the lug overlaps a portion of the carrier 13 and a fiat surface 103 on the lug lies adjacent the overlapped carrier portion to lock the gear member against rotation. This locking action holds the gear member 97 with the truncated side 103 thereof presented toward the rack 101 so that there is no meshed engagement with the latter and this gear member will then be disabled and nonrotatable.

From the accompanying drawings and the foregoing detailed description it will now be readily understood that this invention provides novel transfer mechanism of a relatively simple construction and which will function quietly and with minimum shock while operating at very high speeds. It will also be seen that since the articles are all held in a centered relation on the axes of the holder units, the movement of the articles from one station to another is accomplished by a simple one-direction movement for the holder units which entirely eliminates any slap of the holder units against the die members. Moreover since the articles are held in a centered relation on the axes of the holder units, there will be no gyratory or centrifugal action tending to cause throwing of the articles and, in addition, this centered relation permits the articles to be held by a gripping engagement against vertically opposite sides thereof and also permits the holder units to operate very close to, or even in contacting engagement with, the front face of the die mount. It will be seen further that this close position of the holder units relative to the die mount provides for a more positive and accurate movement of the blanks into the die openings and also permits the ram of the fabricating machine to approach very close to the die mount so that only short die punches will be needed and such short punches will be much less subject to breakage.

Addittionally it will be seen that the holder units each includes a lower portions supported in a manner to permit such portion to fall away freely in the event of breakage of one of the support arms of such lower portion. It will likewise be seen that a turn-over movement for the articles is achieved in a novel manner and without need for rotation of the entire holder unit, and that the holder units can be operated with or without such a turn-over movement as may be desired.

Although the transfer mechanism of this invention has been illustrated and described herein to a somewhat detailed extent, it will be understood, of course, that the invention is not to be regarded as being limited correspondingly in scope but includes all changes and modifications coming within the terms of the claims hereof.

Having thus described my invention, I claim:

1. In transfer mechanism for moving an article from one work station to another: a support means; a carrier movable on said support means and having stem means projecting therefrom on the side nearest said stations and provided with a transverse article-receiving opening; means for moving said carrier for selectively locating said opening in a feeding position adjacent one or the other of said stations; holder members on said stem means and disposed on a common axis and having gripping portions extending into said opening for holding engagement with the article on opposite sides thereof; one of said holder members being rotatable and the gripping portion thereof being shaped to provide a drive connection with said article for a turn-over movement of the latter, the other of said holder members supporting said article for rotation by said one holder member; and means for rotating said one holder member to effect a turnover of said article, said one holder member providing the only drive to said article to effect the turnover thereof.

2. In transfer mechanism for moving an article from one work station to another: a support means; a carrier movable on said support means and having hollow stem means projecting therefrom on the side nearest said stations and provided with a transverse article-receiving opening; means for moving said carrier for selectively locating said opening in a feeding position adjacent one or the other of said stations; holder members in said stem means and disposed on a common axis and having gripping portions extending into said opening for holding engagement with the article on opposite sides thereof; one of said holder members comprising rotatable spindle means and the gripping portion thereof being shaped to provide a drive connection with said article for a turn-over movement of the latter, the other of said holder members supporting said article for rotation by said one holder member; spring means acting to normally maintain said drive connection with said article; and means for rotating said spindle means to rotate said one holder member and turn over said article, said one holder member providing the only drive to said article for turning over the latter.

3. In transfer mechanism for moving an article from one work station to another: a support means; carrier movable on said support means and having hollow stern means projecting therefrom on the side nearest said stations and provided with a transverse article-receiving opening; means for moving said carrier for selectively locating said opening in a feeding position adjacent one or the other of said stations; holder members in said stem means and disposed on a common axis and having gripping portions extending into said opening for holding engagement with the article on opposite sides thereof; one of said holder members comprising a gripping portion adapted to engage the article and to provide a turnover drive connection between the article and the gripping portion, and a spindle extending along said axis, said one holder member including means for adjusting the overall length of said one holder member along said axis; means biasing said one holder member toward the other of said holder members and to a predetermined position along said axis; means biasing the other of said holder members toward said one holder member and said other holder member supporting said article for rotation by said one holder member, adjustable means for limiting the movement of said other holder member toward said one holder member by the bias thereon; and means for rotating said spindle means to rotate said one holder member to eifect a turnover of said article, said one holder member providing the only drive to said article to efifect a turnover thereof.

4. In transfer mechanism as defined in claim 3 wherein said hollow stem means comprises a tubular member coaxial with said axis and supporting said holder members and means connecting said tubular member to said carrier for bodily adjustment along said axis.

5. In an article transfer mechanism, a holder unit comprising a sleeve member having an axial passage therein, a second member connected with one end of said sleeve member in spaced axial relation relative thereto to provide an article-receiving opening therebetween, an article engaging member supported by said second member at one side of said opening and coaxial with said sleeve member, spindle means rotatable in said sleeve member and having gripping means projecting into said opening along said axis, spring means connected between said second member and said article engaging member to urge the latter axially to press an article against said gripping means, means for limiting the movement of said article-engaging member along said axis by the bias thereon, and means for rotating said spindle means to effect a turnover of an article gripped between said gripping means and said article engaging member.

6. In an article transfer mechanism, the structure defined in claim 5 and further comprising means in said sleeve biasing said spindle means and gripping means to a predetermined position in said passage and means supporting said sleeve for bodily adjustment axially to adjust the position of said gripping means and said article engaging member.

7. In a transfer mechanism according to claim 5 wherein said connection between said sleeve member and said second member comprises a pair of arms spanning said opening and located on opposite sides of the axis of said passage, said arms being secured to said sleeve member, separable pin means connecting said arms to the second member whereby said second member will separate from a 16 said arms and fall in the event of breakage of one of said References Cited by the Examiner arms- UNITED STATES PATENTS 8. In an artlcle transfer mechanism the structure as defined in claim 6, wherein said article engaging member 230,638 8/1880 has a fiat surface which engages the article and said ar- 5 2,352,632 7/1944 Heyman 10-466 ticle gripping means has a V-shaped surface for engag- 2825075 3/1958 De ing said article, the surface on said article gripping mem- 3,105,399 10/1963 Strugala et ber having a chamfer at its periphery to facilitate movement of the article into position to be gripped. ANDREW JUHASZPH-mary Examiner 

1. IN TRANSFER MECHANISM FOR MOVING AN ARTICLE FROM ONE WORK STATION TO ANOTHER: A SUPPORT MEANS; A CARRIER MOVABLE ON SAID SUPPORT MEANS AND HAVING STEM MEANS PROJECTING THEREFROM ON THE SIDE NEAREST SAID STATIONS AND PROVIDED WITH A TRANSVERSE ARTICLE-RECEIVING OPENING; MEANS FOR MOVING SAID CARRIER FOR SELECTIVELY LOCATING SAID OPENING IN A FEEDING POSITION ADJACENT ONE OR THE OTHER OF SAID STATIONS; HOLDER MEMBERS ON SAID STEM MEANS AND DISPOSED ON A COMMON AXIS AND HAVING GRIPPING PORTIONS EXTENDING INTO SAID OPENING FOR HOLDING ENGAGEMENT WITH THE ARTICLE ON OPPOSITE SIDES THEREOF; ONE OF SAID HOLDER MEMBERS 